Mild Cold Exposure Research Articles

Preliminary study on the effects of boysenberry juice intake on brown adipose tissue activity in healthy adults

Brown adipose tissue (BAT) plays an important role in energy metabolism because it uses fatty acids for thermogenesis during cold exposure. Preclinical studies found that boysenberry anthocyanins (BoyACs) activate BAT. Therefore, the aim of this preliminary study was to evaluate how BoyAC intake affects BAT in humans. We performed an open-label single-arm nonrandomized study in healthy volunteers. Before and after 4 weeks of daily consumption of 100 ml boysenberry juice (BoyJ) containing 61 mg of BoyACs, participants were assessed at 24 °C and then after 1 h of mild cold exposure (18 °C). An infrared thermography camera was used to measure skin surface temperatures in the supraclavicular BAT region (Tscv) and the non-BAT region of the upper chest (Tch). Energy metabolism was measured by indirect calorimetry. For each endpoint, we calculated Δ as the difference between values before and after cold exposure and compared the values before and after BoyJ intake. 10 volunteers participated (age: 36.1 ± 4.1, body mass index (BMI): 20.9 ± 0.6). After BoyJ intake, ΔTscv-ch was significantly higher (p = 0.029), but Δ energy expenditure, Δ fat oxidation, and Δ carbohydrate oxidation were not significantly different. We found a significant positive correlation between BMI and Δfat oxidation with BoyJ intake. The results indicate that 4 weeks of BoyJ intake activates cold-induced thermogenesis in the scv-BAT but does not have a significant effect on energy metabolism. BoyJ intake may increase fat oxidation during cold exposure in individuals with higher BMI.Trial registry number: UMIN000043476, 05/03/2021.

The application of heating film to hands reduces the decline in manual dexterity performance associated with cold exposure.

Exposure to cold temperatures decreases finger temperature (Tfing) and dexterity. Decreased manual function and dexterity can be serious safety risks, especially in tasks that require fine motor movements that must be performed outdoors. The aim of this study was to determine whether hand heating with a minimal power requirement (14.8W) results in a smaller reduction in Tfing and manual dexterity performance during mild cold exposure compared to a non-heated control condition. In a randomized crossover design, twenty-two healthy participants were exposed to a moderately cold environment (5 ºC) for 90min. One condition had no intervention (CON), while the other had the palmar and dorsal hands heated (HEAT) by using electric heating films. Tfing and cutaneous vascular conductance (CVC) were continuously monitored using laser Doppler flowmetry. Manual dexterity performance and cognitive function were assessed by the Grooved Pegboard Test (GPT) and Stroop Color-Word (SCW) test, respectively, during the baseline period and every 30min during the cold exposure. After the cold exposure, Tfing was higher in HEAT relative to CON (CON 9.8 vs. HEAT 13.7ºC, p < 0.0001). GPT placing time, as an index of dexterity performance, was also shorter in HEAT by 14.5% (CON 69.10 ± 13.08 vs. HEAT 59.06 ± 7.99s, p < 0.0001). There was no difference in CVC between the two conditions during the cold exposure (p > 0.05 for all). Cognitive function was similar between two conditions (p > 0.05 for all). The proposed hand heating method offers a practical means of heating fingers to maintain dexterity throughout prolonged cold exposure.

Association between thermogenic brown fat and genes under positive natural selection in circumpolar populations

BackgroundAdaptation to cold was essential for human migration across Eurasia. Non-shivering thermogenesis through brown adipose tissue (BAT) participates in cold adaptation because some genes involved in the differentiation and function of BAT exhibit signatures of positive natural selection in populations at high latitudes. Whether these genes are associated with the inter-individual variability in BAT thermogenesis remains unclear. In this study, we evaluated the potential associations between BAT activity and single nucleotide polymorphisms (SNPs) in candidate gene regions in East Asian populations.MethodsBAT activity induced by mild cold exposure was measured in 399 healthy Japanese men and women using fluorodeoxyglucose-positron emission tomography and computed tomography (FDG-PET/CT). The capacity for cold-induced thermogenesis and fat oxidation was measured in 56 men. Association analyses with physiological traits were performed for 11 SNPs at six loci (LEPR, ANGPTL8, PLA2G2A, PLIN1, TBX15-WARS2, and FADS1) reported to be under positive natural selection. Associations found in the FDG-PET/CT population were further validated in 84 healthy East Asian men and women, in whom BAT activity was measured using infrared thermography. Associations between the SNP genotypes and BAT activity or other related traits were tested using multiple logistic and linear regression models.ResultsOf the 11 putative adaptive alleles of the six genes, two intronic SNPs in LEPR (rs1022981 and rs12405556) tended to be associated with higher BAT activity. However, these did not survive multiple test comparisons. Associations with lower body fat percentage, plasma triglyceride, insulin, and HOMA-IR levels were observed in the FDG-PET/CT population (P < 0.05). Other loci, including TBX15-WARS2, which is speculated to mediate cold adaptation in Greenland Inuits, did not show significant differences in BAT thermogenesis.ConclusionsOur results suggest a marginal but significant association between LEPR SNPs. However, robust supporting evidence was not established for the involvement of other loci under positive natural selection in cold adaptation through BAT thermogenesis in East Asian adults. Given the pleiotropic function of these genes, factors other than cold adaptation through BAT thermogenesis, such as diet adaptation, may contribute to positive natural selection at these loci.

Abstract Tu036: Adipose tissue plasticity in response to early pathological stress on the heart and mediation by adipose thermogenic activation

Background: Cardiovascular diseases (CVD) are the leading cause of death globally, accounting for approximately 17.9 million mortalities per year. Previous studies have shown that there is an early response of white and brown adipose tissue (WAT and BAT, respectively) to pathological stress on the heart prior to cardiac dysfunction. Interestingly, human subjects with detectable BAT activity (a thermogenic tissue) exhibit a reduced risk of Congestive Heart Failure, but the mechanism for this is unclear. We hypothesized that increasing the thermogenic acitivity of adipose tissue would be beneficial during the initial cardiac hypertrophic signaling prior to the development of compensatory hypertrophy. Methods: We studied both WAT and BAT in male and female C57BL/6J mice subjected to cardiac pressure overload via transaortic constriction (TAC). 24 hours post-surgery, mice were subjected to room temperature (RT) 22° C or mild cold 16°C to stimulate BAT activation for 48 hours after which tissues were collected. The study groups included: SHAM RT, TAC RT, SHAM COLD, TAC COLD. We used uncoupling protein 1 knockout (UCP1-KO) mice, with impaired thermogenic activity as a negative control. Results: At 72 hours post tac surgery, expression of thermogenic and metabolic genes remained unchanged in BAT and WAT of both sexes. However, mild cold exposure resulted in an increase in UCP1 expression in BAT of male, but not female mice while other metabolic and thermogenic gene markers’ expression was increased in a sex-specific manner. Adaptations to scWAT were more moderate than BAT, with an increase in Ucp1 after cold exposure in both sexes. Moreover, 48 hours of cold exposure attenuated expression of gene markers for hypertrophic signaling in the heart during TAC. Importantly, these adaptations were absent in UCP1-KO mice, signifying that intact thermogenic activity in adipose tissue was required for the attenuated expression of hypertrophic markers in the heart. Interestingly, cardiac fibrosis markers were downregulated with TAC-Cold in male mice only, suggesting a stronger response compared to female mice. Conclusions: Our findings demonstrate that pathological stress on the heart during TAC does not impact adipose tisse thermogenesis. Additionally, activating thermogenic gene expression of adipose tissue via cold exposure mediates the early induction of hypertrophic signaling in the heart within 72 hours of TAC. Notably, adipose tissue plasticity is sex-specific.

Immune response to cold exposure: Role of γδ T cells and TLR2-mediated inflammation.

The mammalian body possesses remarkable adaptability to cold exposure, involving intricate adjustments in cellular metabolism, ultimately leading to thermogenesis. However, cold-induced stress can impact immune response, primarily through noradrenaline-mediated pathways. In our study, we utilized a rat model subjected to short-term or long-term mild cold exposure to investigate systemic immune response during the cold acclimation. To provide human relevance, we included a group of regular cold swimmers in our study. Our research revealed complex relationship between cold exposure, neural signaling, immune response, and thermogenic regulation. One-day cold exposure triggered stress response, including cytokine production in white adipose tissue, subsequently activating brown adipose tissue, and inducing thermogenesis. We further studied systemic immune response, including the proportion of leukocytes and cytokines production. Interestingly, γδ T cells emerged as possible regulators in the broader systemic response, suggesting their possible contribution in the dynamic process of cold adaptation. We employed RNA-seq to gain further insights into the mechanisms by which γδ T cells participate in the response to cold. Additionally, we challenged rats exposed to cold with the Toll-like receptor 2 agonist, showing significant modulation of immune response. These findings significantly contribute to understanding of the physiological acclimation that occur in response to cold exposure.

UCP1 expression in human brown adipose tissue is inversely associated with cardiometabolic risk factors.

Brown adipose tissue (BAT) is a therapeutic target for obesity. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) is commonly used to quantify human BAT mass and activity. Detectable 18F-FDG uptake by BAT is associated with reduced prevalence of cardiometabolic disease. However, 18F-FDG uptake may not always be a reliable marker of BAT thermogenesis, for example, insulin resistance may reduce glucose uptake. Uncoupling protein 1 (UCP1) is the key thermogenic protein in BAT. Therefore, we hypothesised that UCP1 expression may be altered in individuals with cardiometabolic risk factors. We quantified UCP1 expression as an alternative marker of thermogenic capacity in BAT and white adipose tissue (WAT) samples (n = 53) and in differentiated brown and white pre-adipocytes (n = 85). UCP1 expression in BAT, but not in WAT or brown/white differentiated pre-adipocytes, was reduced with increasing age, obesity, and adverse cardiometabolic risk factors such as fasting glucose, insulin, and blood pressure. However, UCP1 expression in BAT was preserved in obese subjects of <40 years of age. To determine if BAT activity was also preserved in vivo, we undertook a case-control study, performing 18F-FDG scanning during mild cold exposure in young (mean age ∼22 years) normal weight and obese volunteers. 18F-FDG uptake by BAT and BAT volume were similar between groups, despite increased insulin resistance. 18F-FDG uptake by BAT and UCP1 expression are preserved in young obese adults. Older subjects retain precursor cells with the capacity to form new thermogenic adipocytes. These data highlight the therapeutic potential of BAT mass expansion and activation in obesity.

Genetic evidence for involvement of β2-adrenergic receptor in brown adipose tissue thermogenesis in humans

BackgroundSympathetic activation of brown adipose tissue (BAT) thermogenesis can ameliorate obesity and related metabolic abnormalities. However, crucial subtypes of the β-adrenergic receptor (AR), as well as effects of its genetic variants on functions of BAT, remains unclear in humans. We conducted association analyses of genes encoding β-ARs and BAT activity in human adults.MethodsSingle nucleotide polymorphisms (SNPs) in β1-, β2-, and β3-AR genes (ADRB1, ADRB2, and ADRB3) were tested for the association with BAT activity under mild cold exposure (19 °C, 2 h) in 399 healthy Japanese adults. BAT activity was measured using fluorodeoxyglucose-positron emission tomography and computed tomography (FDG-PET/CT). To validate the results, we assessed the effects of SNPs in the two independent populations comprising 277 healthy East Asian adults using near-infrared time-resolved spectroscopy (NIRTRS) or infrared thermography (IRT). Effects of SNPs on physiological responses to intensive cold exposure were tested in 42 healthy Japanese adult males using an artificial climate chamber.ResultsWe found a significant association between a functional SNP (rs1042718) in ADRB2 and BAT activity assessed with FDG-PET/CT (p < 0.001). This SNP also showed an association with cold-induced thermogenesis in the population subset. Furthermore, the association was replicated in the two other independent populations; BAT activity was evaluated by NIRTRS or IRT (p < 0.05). This SNP did not show associations with oxygen consumption and cold-induced thermogenesis under intensive cold exposure, suggesting the irrelevance of shivering thermogenesis. The SNPs of ADRB1 and ADRB3 were not associated with these BAT-related traits.ConclusionsThe present study supports the importance of β2-AR in the sympathetic regulation of BAT thermogenesis in humans. The present collection of DNA samples is the largest to which information on the donor’s BAT activity has been assigned and can serve as a reference for further in-depth understanding of human BAT function.

Neuregulin 4 mediates the metabolic benefits of mild cold exposure by promoting beige fat thermogenesis.

Interorgan crosstalk via secreted hormones and metabolites is a fundamental aspect of mammalian metabolic physiology. Beyond the highly specialized endocrine cells, peripheral tissues are emerging as an important source of metabolic hormones that influence energy and nutrient metabolism and contribute to disease pathogenesis. Neuregulin 4 (Nrg4) is a fat-derived hormone that protects mice from nonalcoholic steatohepatitis (NASH) and NASH-associated liver cancer by shaping hepatic lipid metabolism and the liver immune microenvironment. Despite its enriched expression in brown fat, whether NRG4 plays a role in thermogenic response and mediates the metabolic benefits of cold exposure are areas that remain unexplored. Here we show that Nrg4 expression in inguinal white adipose tissue (iWAT) is highly responsive to chronic cold exposure. Nrg4 deficiency impairs beige fat induction and renders mice more susceptible to diet-induced metabolic disorders under mild cold conditions. Using mice with adipocyte and hepatocyte-specific Nrg4 deletion, we reveal that adipose tissue-derived NRG4, but not hepatic NRG4, is essential for beige fat induction following cold acclimation. Furthermore, treatment with recombinant NRG4-Fc fusion protein promotes beige fat induction in iWAT and improves metabolic health in mice with diet-induced obesity. These findings highlight a critical role of NRG4 in mediating beige fat induction and preserving metabolic health under mild cold conditions.

OR07-03 UCP1 Expression In Human Brown Adipose Tissue Is Inversely Associated With Cardiometabolic Risk Factors

Abstract Disclosure: T. Kwok: None. L.E. Ramage: None. K.J. Suchacki: None. C. Gray: None. K. Alexandra: None. L.D. Boyle: None. R.K. Semple: None. S.I. Semple: None. T. MacGillivray: None. E.J. van Beek: None. S. Wakelin: None. R.H. Stimson: None. Brown adipose tissue (BAT) is a promising therapeutic target for obesity. 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG PET) is the most commonly used imaging modality to quantify human BAT activity. 18F-FDG uptake may be reduced in obesity but insulin resistance has been suggested as a potential confounding factor. Uncoupling protein 1 (UCP1) is the key thermogenic protein in BAT and thus serves as a surrogate measure of BAT thermogenic capacity. We quantified UCP1 expression in paired BAT and white adipose tissue (WAT) samples from 141 patients undergoing elective neck surgery. UCP1 mRNA was quantified in whole tissue (n=53) and differentiated pre-adipocytes (n=88). Data are presented as mean ± SEM. Individuals with high UCP1 expression in whole BAT (&amp;gt;2 arbitrary units) were younger (44.2 ± 3.5 vs 55.7 ± 2.0 years) with lower BMI (26.5 ± 1.2 vs 30.1 ± 1.0kg/m2), waist circumference (87.9 ± 2.9 vs 101.1 ± 2.6cm), waist-hip ratio (0.86 ± 0.01 vs 0.92 ± 0.01), fat percentage (29.1 ± 2.6 vs 35.3 ± 1.7%), insulin resistance (HOMA-IR 1.44 ± 0.18 vs 2.69 ± 0.35), systolic (131 ± 6 vs 143 ± 4mmHg) and diastolic blood pressure (79 ± 3 vs 86 ± 2mmHg) (all P&amp;lt;0.05). BAT UCP1 expression was lower in subjects on beta-blockers or with existing hypertension. BAT (but not WAT) UCP1 expression correlated negatively with age (r=−0.305), weight (r=−0.374), waist circumference (r=−0.296), fat mass (r=−0.388) and BMI (r=−0.282) (all P&amp;lt;0.05). However, UCP1 levels in differentiated brown adipocytes were not associated with any of the above measurements. In multiple regression, age was the only independent predictor of high BAT UCP1 expression. Interestingly, BAT UCP1 levels were not reduced in obese subjects aged &amp;lt;40 years. To determine whether BAT activity was preserved in young obese subjects in vivo, we performed 18F-FDG-PET/MR scanning during mild cold exposure (16-17°C) in 6 normal weight (BMI 22 ± 1kg/m2) and 6 obese (BMI 32 ± 1kg/m2) age-matched (22 ± 1 years) subjects. BAT 18F-FDG uptake (standard uptake value 5.1 ± 0.5 vs 4.2 ± 0.6 g/mL) and volume (69 ± 14 vs 72 ± 32 cm3) were similar between weight groups, despite greater insulin resistance in obese subjects (fasting glucose 5.5 ± 0.2 vs 4.3 ± 0.1mmol/L, insulin 11.9 ± 1.3 vs 5.8 ± 0.9mU/L, HOMA-IR 2.9 ± 0.3 vs 1.1 ± 0.2, free fatty acids 465 ± 78 vs 240 ± 34µM, all P&amp;lt;0.05), suggesting that 18F-FDG uptake by BAT is not significantly affected by insulin resistance. In conclusion, BAT UCP1 expression is reduced in individuals with adverse cardiometabolic risk factors, but these subjects retain brown pre-adipocytes with the capacity to form new thermogenic adipocytes after appropriate stimulation. UCP1 expression and cold-induced 18F-FDG uptake by BAT is preserved in young obese subjects. These data highlight the therapeutic potential of BAT mass expansion and activation as a therapeutic strategy to ameliorate the cardiometabolic consequences of obesity. Presentation: Thursday, June 15, 2023

Image registration and mutual thresholding enable low interimage variability across dynamic MRI measurements of supraclavicular brown adipose tissue during mild cold exposure.

Activated brown adipose tissue (BAT) enhances lipid catabolism and improves cardiometabolic health. Quantitative MRI of the fat fraction (FF) of supraclavicular BAT (scBAT) is a promising noninvasive measure to assess BAT activity but suffers from high scan variability. We aimed to test the effects of coregistration and mutual thresholding on the scan variability in a fast (1 min) time-resolution MRI protocol for assessing scBAT FF changes during cold exposure. Ten volunteers (age 24.8 ± 3.0 years; body mass index 21.2 ± 2.1 kg/m2 ) were scanned during thermoneutrality (32°C; 10 min) and mild cold exposure (18°C; 60 min) using a 12-point gradient-echo sequence (70 consecutive scans with breath-holds, 1.03 min per dynamic). Dynamics were coregistered to the first thermoneutral scan, which enabled drawing of single regions of interest in the scBAT depot. Voxel-wise FF changes were calculated at each time point and averaged across regions of interest. We applied mutual FF thresholding, in which voxels were included if their FF was greater than 30% FF in the reference scan and the registered dynamic. The efficacy of the coregistration was determined by using a moving average and comparing the mean squared error of residuals between registered and nonregistered data. Registered scBAT ΔFF was compared with single-scan thresholding using the moving average method. Registered scBAT ΔFF had lower mean square error values than nonregistered data (0.07 ± 0.05% vs. 0.16 ± 0.14%; p < 0.05), and mutual thresholding reduced the scBAT ΔFF variability by 30%. We demonstrate that coregistration and mutual thresholding improve stability of the data 2-fold, enabling assessment of small changes in FF following cold exposure.

JS-HR-12: BASIC RESEARCH: ELUCIDATION OF “MOSAIC” PATHOGENESIS OF HYPERTENSION

Basic research plays critical roles in elucidating the “mosaic” pathogenesis of hypertension and developing its treatment. In the field of brain and autonomic nervous system, Chen et al. demonstrated that mild cold exposure elicits autonomic dysregulation, such as increased sympathetic activity and decreased baroreflex sensitivity, and poor sleep quality, causing blood pressure (BP) elevation in normotensive rats. This finding may have critical implications for the cardiovascular event occurrence with low ambient temperature. Domingos-Souza et al. showed that the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of carotid sinus stimulation in spontaneously hypertensive rats (SHRs), proposing a rationale for improving baroreflex activation therapy in humans. In the kidney, Kasacka et al. showed that activity of Wnt/β-catenin pathway is increased in SHRs and 2K1C hypertensive rats, while it is inhibited in DOCA-salt rats. Intrarenal renin-angiotensin system (RAS) is involved in BP regulation. In renal damage with an impaired glomerular filtration barrier, liver-derived angiotensinogen filtered through damaged glomeruli regulates intrarenal RAS activity. Matsuyama et al. further showed that the glomerular filtration of liver-derived angiotensinogen depending on glomerular capillary pressure causes circadian rhythm of the intrarenal RAS. Otsuki et al. revealed that TWIST1, a transcription factor regulating mesodermal embryogenesis, transcriptionally upregulates complement 3, which has been demonstrated to activate intrarenal RAS, in the glomerular mesangial cells from SHRs. The RAS in the vascular system also contributes to BP regulation. Soring nexins (SNXs) are cellular sorting proteins and can regulate the expression and function of G protein-coupled receptors (GPCRs). Liu C et al. demonstrated that SNX1 knockout mice exhibit hypertension through vasoconstriction mediated by increased expression of GPCR AT1R within the arteries. Liu X et al. found that sirtuin 6 (SIRT6) expression is downregulated in the aortae of aged rats and showed that SIRT6 knockdown enhances angiotensin II-induced vascular adventitial aging by activating NF-κB pathway in vitro studies. The studies investigating extracellular vesicles (EVs) and gut microbiota have been increased. Ochiai-Homma et al. showed that pendrin in urinary EVs can be a useful biomarker for diagnosis and treatment of primary aldosteronism. Wu et al. demonstrated that captopril has the potential to rebalance the dysbiotic gut microbiota of DOCA-salt hypertensive rats. Several reports indicate the potential treatment for hypertension and the associated organ damages: rivaroxaban in cardiac hypertrophy; nebivolol, maximakinin, and Pinggan-Qianyang in hypertension; and melatonin and crocin in gestational hypertension.

Effects of correlated color temperature of light on thermal comfort, thermophysiology and cognitive performance

Anecdotal evidence suggests that the correlated color temperature (CCT) of light can affect thermal comfort. Previous literature mostly investigated this effect over a short duration (<1 h) and often attributed it to the hue-heat hypothesis (color-temperature association), which posits that the visual experience of blue colors (high CCT) results in a cooler temperature sensation than red/yellow colors (low CCT) do. However, with longer duration, non-visual effects of CCT that elicit physiological changes may be at play additionally. Therefore, we contrasted two CCTs with relatively long exposures (>2 h; 2700 K vs. 5700 K with 500 lux illuminance at the eye) in office-like settings during mild cold exposure (17 °C) using a within-subject design (N = 16). The results indicate that CCT did not significantly affect thermal sensation in mild cold, which may be explained by the large interindividual variation in the color-temperature association. Interestingly, 5700 K even improved thermal comfort, decreased perceived shivering, and, after 1-h exposure, increased energy expenditure. Moreover, visual comfort was not significantly moderated by CCT, but 5700 K improved comprehensive cognitive performance. Concurrently, arousal and alertness were higher in 5700 K, potentially indicating greater non-visual effects in 5700 K. Further analysis revealed that thermal comfort significantly correlated with perceived shivering and visual comfort, but not with the color sensation of the light. Together, the results provide no support for the hue-heat hypothesis under mildly cold conditions and suggest that high CCT enhanced thermal comfort, alertness, arousal, and cognitive performance, likely via non-visual mechanisms that built up over longer exposure durations.

Effect of Acute Cold Stress on Neuroethology in Mice and Establishment of Its Model.

Simple SummaryUnavoidable cold stress has widespread and complex effects on humans and animals in cold regions. A series of abnormal changes in behavior, emotion and neuroendocrine system occur in response to cold stress. However, the neglect of these physiological changes and the difficulty of defining cold stress combine to hinder the in-depth study and understanding of neurobehavior under cold stress. Therefore, our study established cold-stress models of mice with different intensities to systematically observe the neurobehavioral changes and to summarize the neurobehavioral characteristics and patterns. The results of the open field test and elevated plus maze test show that mild acute cold exposure promoted spontaneous movements, increased exploratory behaviors, and improved anxiety. As the intensity of cold exposure increased, cold exposure negatively affected spontaneous movements, exploratory behaviors and anxiety emotion. Combined with the relevant stress hormones, the activation of the hypothalamic–pituitary–adrenal axis and locus coeruleus-noradrenergic system with varying degrees were found to underlie these behavioral and emotional fluctuations. This study provides new insights into the interaction pattern between animals and the environment, and the understanding is beneficial to promoting animal welfare and its assessment in cold regions.Cold environment is an inevitable stress source for humans and livestock in cold areas, which easily induce a cold stress response and then cause a series of abnormal changes in energy metabolism, neuroendocrine system, behavior and emotion. Homeostasis is maintained by the unified regulation of the autonomic nervous system, endocrine system, metabolism and behavior under cold exposure. Behavior is an indispensable part of the functional regulation of the body to respond to environmental changes. At present, the behavioral changes caused by cold exposure are unclear or even chaotic due to the difficulty of defining cold stress. Therefore, this study aims to systematically observe the changes in spontaneous movement, exploratory behavior and anxiety of mice under different intensity cold exposure and summarize the characteristics and behavior traits combined with relevant blood physiological indexes under corresponding conditions. Mice models of cold stress with different intensities were established (cold exposure gradients were 22 °C, 16 °C, 10 °C and 4 °C, and time gradients of each temperature were 2 h, 4 h, 6 h, 8 h, 10 h and 12 h). After the corresponding cold exposure treatment, mice immediately carried out the open field test(OFT) and elevated plus maze test (PMT) to evaluate their spontaneous movement, exploratory behavior and anxiety. Subsequently, blood samples were collected and used for the determination of corticosterone (Cort), corticotropin-releasing hormone (CRH), epinephrine (E), norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) by enzyme-linked immunosorbent assay (ELISA). Spontaneous movement of mice increased under 22 °C cold exposure, but their exploration behavior did not significantly change, and their anxiety improved at the initial stage. The spontaneous movement and anxiety of mice increased in the initial stage and decreased in the later stage under cold exposure at 16, 10 and 4 °C and the exploratory behavior was inhibited. The hypothalamic–pituitary–adrenal (HPA) axis and locus coeruleus-noradrenergic (LC/NE) system were activated by cold stress and fluctuated with different intensities of cold exposure. Meanwhile, serum DA increased, and 5-HT was the opposite under different intensities of cold exposure. In conclusion, mild acute cold exposure promoted the spontaneous movement, increased exploratory behavior and improved anxiety. As the intensity of cold exposure increases, cold exposure had a negative effect on spontaneous movement, exploratory behavior and emotion. The physiological basis of these behavioral and emotional changes in mice under different intensity cold stimulation is the fluctuation of Cort, CRH, E, NE, DA and 5-HT.

Brown-fat-mediated tumour suppression by cold-altered global metabolism

Glucose uptake is essential for cancer glycolysis and is involved in non-shivering thermogenesis of adipose tissues1–6. Most cancers use glycolysis to harness energy for their infinite growth, invasion and metastasis2,7,8. Activation of thermogenic metabolism in brown adipose tissue (BAT) by cold and drugs instigates blood glucose uptake in adipocytes4,5,9. However, the functional effects of the global metabolic changes associated with BAT activation on tumour growth are unclear. Here we show that exposure of tumour-bearing mice to cold conditions markedly inhibits the growth of various types of solid tumours, including clinically untreatable cancers such as pancreatic cancers. Mechanistically, cold-induced BAT activation substantially decreases blood glucose and impedes the glycolysis-based metabolism in cancer cells. The removal of BAT and feeding on a high-glucose diet under cold exposure restore tumour growth, and genetic deletion of Ucp1—the key mediator for BAT-thermogenesis—ablates the cold-triggered anticancer effect. In a pilot human study, mild cold exposure activates a substantial amount of BAT in both healthy humans and a patient with cancer with mitigated glucose uptake in the tumour tissue. These findings provide a previously undescribed concept and paradigm for cancer therapy that uses a simple and effective approach. We anticipate that cold exposure and activation of BAT through any other approach, such as drugs and devices either alone or in combination with other anticancer therapeutics, will provide a general approach for the effective treatment of various cancers.

P53 Regulates a miRNA-Fructose Transporter Axis in Brown Adipose Tissue Under Fasting.

Active thermogenic adipocytes avidly consume energy substrates like fatty acids and glucose to maintain body temperature upon cold exposure. Despite strong evidence for the involvement of brown adipose tissue (BAT) in controlling systemic energy homeostasis upon nutrient excess, it is unclear how the activity of brown adipocytes is regulated in times of nutrient scarcity. Therefore, this study aimed to scrutinize factors that modulate BAT activity to balance thermogenic and energetic needs upon simultaneous fasting and cold stress. For an unbiased view, we performed transcriptomic and miRNA sequencing analyses of BAT from acutely fasted (24 h) mice under mild cold exposure. Combining these data with in-depth bioinformatic analyses and in vitro gain-of-function experiments, we define a previously undescribed axis of p53 inducing miR-92a-1-5p transcription that is highly upregulated by fasting in thermogenic adipocytes. p53, a fasting-responsive transcription factor, was previously shown to control genes involved in the thermogenic program and miR-92a-1-5p was found to negatively correlate with human BAT activity. Here, we identify fructose transporter Slc2a5 as one direct downstream target of this axis and show that fructose can be taken up by and metabolized in brown adipocytes. In sum, this study delineates a fasting-induced pathway involving p53 that transactivates miR-92a-1-5p, which in turn decreases Slc2a5 expression, and suggests fructose as an energy substrate in thermogenic adipocytes.

157-OR: High-Fat–Diet Feeding Disrupts Thermal Responsiveness of AgRP Neurons

To defend energy homeostasis in the cold requires energy expenditure (to support thermogenesis) and energy intake increase, enabling core temperature to be maintained with no change to body fat stores. When acutely housed at a mild cold (14°C) , mice increase both food intake and heat production rapidly (∼minutes) , and these responses occur in parallel. We hypothesized a role for Agouti-related peptide (AgRP) neurons in this response and find their activity is regulated by thermal sensory input, and they increase activity, measured by Fos induction and fiber photometry, upon cold sensation, and reduce activity as sensed temperatures rise. By inhibiting AgRP neurons during acute cold exposure, we also find this increase in AgRP neuron activity is required for the hyperphagic response to cold. Recent evidence found high-fat diet (HFD) feeding reduced AgRP neuron responsiveness to gastric hormones and standard chow diet presentation, and we hypothesized that their response to thermal input might also be blunted. We find that although 12-week HFD-fed mice exhibit intact thermogenic responses to cold and defend a normal core body temperature, they fail to increase energy intake and consequently experience weight loss not observed in chow-fed controls. This uncoupling of energy intake from energy expenditure is present even after a shorter, 2-week exposure to HFD-feeding, implying a role for diet separate from obesity in the phenotype. Using Agrp-Cre/GFP marker mice, we find acute cold exposure rapidly induces Fos in chow-fed mice, but this response is lacking in HFD-fed mice. This effect correlates with a failure to increase hypothalamic Agrp mRNA even after five days of mild cold exposure. Using photometry to measure AgRP neuron calcium activity, we find activity changes associated with thermal input, both cold and warm, are blunted with HFD feeding. Further testing will determine exactly how the food intake response to cold has become uncoupled from other thermoregulatory responses across the development of obesity. Disclosure J.D.Deem: None. T.P.Doan: None. B.N.Phan: None. K.Ogimoto: None. S.J.W.Hu: None. B.Wu: None. M.W.Schwartz: None. G.J.Morton: Research Support; Novo Nordisk A/S. Funding American Diabetes Association (1-19-PDF-103) ; NIDDK (K01 DK126793) , NIDDK (DK089056) , NIDDK (DK124238) , NIDDK (DK035816) , NIDA (P30 DA048736) , NIDDK (DK035816) , NIDDK (DK17047)

The effect of cold exposure on circulating transcript levels of immune genes in Dutch South Asian and Dutch Europid men

ObjectivesAlthough cold exposure is commonly believed to be causally related to acute viral respiratory infections, its effect on the immune system is largely unexplored. In this study, we determined transcript levels of a large panel of immune genes in blood before and after cold exposure. We included both Dutch Europid and Dutch South Asian men to address whether the immune system is differently regulated in the metabolically vulnerable South Asian population. MethodsFasted blood samples were obtained from nonobese Dutch Europid (n = 11; mean age 26 ± 3 y) and Dutch South Asian (n = 12; mean age 28 ± 3 y) men before and directly after short-term (∼2.5 h) mild cold exposure. Transcript levels of 144 immune genes were measured using a dual-color reverse transcriptase multiplex ligation-dependent probe amplification (dcRT-MLPA) assay. ResultsCold exposure acutely upregulated mRNA levels of GNLY (+35%, P < 0.001) and PRF1 (+45%, P < 0.001), which encode cytotoxic proteins, and CCL4 (+8%, P < 0.01) and CCL5 (+5%, P < 0.05), both pro-inflammatory chemokines. At thermoneutrality, mRNA levels of four markers of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR)-family, involved in inflammasomes, were lower in Dutch South Asians compared to Dutch Europids, namely NLRP2 (−57%, P < 0.05), NLRP7 (−17%, P < 0.05), NLRP10 (−21%, P < 0.05), and NLRC4 (−23%, P < 0.05). ConclusionsMild cold exposure acutely increases mRNA levels of genes involved in cytotoxicity of immune cells in blood. In addition, Dutch South Asians display lower circulating mRNA levels of inflammasome genes compared to Dutch Europids.

Brown adipose tissue thermogenesis among a small sample of reindeer herders from sub-Arctic Finland

IntroductionInterest in human physiological responses to cold stress have seen a resurgence in recent years with a focus on brown adipose tissue (BAT), a mitochondria dense fat specialized for heat production. However, a majority of the work examining BAT has been conducted among temperate climate populations.MethodsTo expand our understanding of BAT thermogenesis in a cold climate population, we measured, using indirect calorimetry and thermal imaging, metabolic rate and body surface temperatures of BAT-positive and BAT-negative regions at room temperature, and mild cold exposure of resting participants from a small sample of reindeer herders (N = 22, 6 females) from sub-Arctic Finland.ResultsWe found that most herders experienced a significant mean 8.7% increase in metabolic rates, preferentially metabolized fatty acids, and maintained relatively warmer body surface temperatures at the supraclavicular region (known BAT location) compared to the sternum, which has no associated BAT. These results indicate that the herders in this sample exhibit active BAT thermogenesis in response to mild cold exposure.ConclusionsThis study adds to the rapidly growing body of work looking at the physiological and thermoregulatory significance of BAT and the important role it may play among cold stressed populations.

Cold Exposure Drives Weight Gain and Adiposity following Chronic Suppression of Brown Adipose Tissue.

Therapeutic activation of thermogenic brown adipose tissue (BAT) may be feasible to prevent, or treat, cardiometabolic disease. However, rodents are commonly housed below thermoneutrality (~20 °C) which can modulate their metabolism and physiology including the hyperactivation of brown (BAT) and beige white adipose tissue. We housed animals at thermoneutrality from weaning to chronically supress BAT, mimic human physiology and explore the efficacy of chronic, mild cold exposure (20 °C) and β3-adrenoreceptor agonism (YM-178) under these conditions. Using metabolic phenotyping and exploratory proteomics we show that transfer from 28 °C to 20 °C drives weight gain and a 125% increase in subcutaneous fat mass, an effect not seen with YM-178 administration, thus suggesting a direct effect of a cool ambient temperature in promoting weight gain and further adiposity in obese rats. Following chronic suppression of BAT, uncoupling protein 1 mRNA was undetectable in the subcutaneous inguinal white adipose tissue (IWAT) in all groups. Using exploratory adipose tissue proteomics, we reveal novel gene ontology terms associated with cold-induced weight gain in BAT and IWAT whilst Reactome pathway analysis highlights the regulation of mitotic (i.e., G2/M transition) and metabolism of amino acids and derivatives pathways. Conversely, YM-178 had minimal metabolic-related effects but modified pathways involved in proteolysis (i.e., eukaryotic translation initiation) and RNA surveillance across both tissues. Taken together these findings are indicative of a novel mechanism whereby animals increase body weight and fat mass following chronic suppression of adaptive thermogenesis from weaning. In addition, treatment with a B3-adrenoreceptor agonist did not improve metabolic health in obese animals raised at thermoneutrality.

Activating Human Adipose Tissue with the β3-Adrenergic Agonist Mirabegron.

An appealing strategy for treatment of metabolic disease in humans is activation of brown adipose tissue (BAT), a thermogenic organ best visualized through 18F-FDG PET/CT. BAT has been activated to varying degrees by mild cold exposure. However, this approach can cause undesirable stress, and there remains no consensus protocol. Here, we describe standardized methods for both acute and chronic activation of BAT using the orally administered β3-adrenergic receptor (AR) agonist, mirabegron. Acute pharmacological stimulation has enabled quantification of whole-body BAT volume and metabolic activity using PET/CT imaging, and chronic stimulation increases these properties of BAT over time.